How to write to USB HD?

[tendril]

Hi,

I'm trying to back up my data using knoppix. I had a Ximeta Netdisk USB hard drive that knoppix automatically mounts to /dev/sda1. However, I cannot write to it no matter what I do. I cleared the read-only flag on it and I edited the fstab to no avail. How can I write to this HD and commence my backup?

[Markus]

How is it formatted?
Can you show the output of: sudo fdisk -l
Is it mounted rw? Output of: mount
To mount everything rw: sudo mount -a
Are users allowed to write and have you tried as su?